In recent years, various members have been formed of a fiber-reinforced plastic (resin) using carbon fibers and the like as a reinforcement.
In the case where a member comprising a fiber-reinforced plastic is fixed to another structural member, in the case where another part or the like is attached to the member comprising a fiber-reinforced plastic, and in the like cases, a through hole is sometimes formed in the member comprising a fiber-reinforced plastic.
When such a through hole is formed, in some cases, delamination occurs around the through hole, or the through hole is formed slantwise by working error.
Also, cracks and the like may be generated around the through hole by fastening a bolt and nut and other fasteners with an excessive force.
To repair such a through hole, there has been available a method in which a tapered hole is formed by removing a portion in the range including the damaged portion around the through hole, a plug that comprises a fiber-reinforced plastic and has a shape such as to fit the tapered hole is bonded to the tapered hole, and a new through hole is re-formed (for example, refer to Patent Literature 1).